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<h1>v_qrdotdiv
</h1>

<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>V_QRDOTDIV divides two real quaternions arrays elementwise q=[x,y]</strong></div>

<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>function q=v_qrdotdiv(x,y) </strong></div>

<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre class="comment">V_QRDOTDIV divides two real quaternions arrays elementwise q=[x,y]

 Inputs:  x(4n,...)
          y(4n,...)   Two real quaternion arrays of equal size

 Outputs: q(4n,...)    The Hadamard quaotient (i.e. ./) of the input arrays
                       If y is omitted then q = x^(-1)

      Copyright (C) Mike Brookes 2000-2012
      Version: $Id: v_qrdotdiv.m 10865 2018-09-21 17:22:45Z dmb $

   VOICEBOX is a MATLAB toolbox for speech processing.
   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You can obtain a copy of the GNU General Public License from
   http://www.gnu.org/copyleft/gpl.html or by writing to
   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</pre></div>

<!-- crossreference -->
<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
This function calls:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
This function is called by:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
<!-- crossreference -->


<h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function q=v_qrdotdiv(x,y)</a>
0002 <span class="comment">%V_QRDOTDIV divides two real quaternions arrays elementwise q=[x,y]</span>
0003 <span class="comment">%</span>
0004 <span class="comment">% Inputs:  x(4n,...)</span>
0005 <span class="comment">%          y(4n,...)   Two real quaternion arrays of equal size</span>
0006 <span class="comment">%</span>
0007 <span class="comment">% Outputs: q(4n,...)    The Hadamard quaotient (i.e. ./) of the input arrays</span>
0008 <span class="comment">%                       If y is omitted then q = x^(-1)</span>
0009 <span class="comment">%</span>
0010 <span class="comment">%      Copyright (C) Mike Brookes 2000-2012</span>
0011 <span class="comment">%      Version: $Id: v_qrdotdiv.m 10865 2018-09-21 17:22:45Z dmb $</span>
0012 <span class="comment">%</span>
0013 <span class="comment">%   VOICEBOX is a MATLAB toolbox for speech processing.</span>
0014 <span class="comment">%   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html</span>
0015 <span class="comment">%</span>
0016 <span class="comment">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span>
0017 <span class="comment">%   This program is free software; you can redistribute it and/or modify</span>
0018 <span class="comment">%   it under the terms of the GNU General Public License as published by</span>
0019 <span class="comment">%   the Free Software Foundation; either version 2 of the License, or</span>
0020 <span class="comment">%   (at your option) any later version.</span>
0021 <span class="comment">%</span>
0022 <span class="comment">%   This program is distributed in the hope that it will be useful,</span>
0023 <span class="comment">%   but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
0024 <span class="comment">%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the</span>
0025 <span class="comment">%   GNU General Public License for more details.</span>
0026 <span class="comment">%</span>
0027 <span class="comment">%   You can obtain a copy of the GNU General Public License from</span>
0028 <span class="comment">%   http://www.gnu.org/copyleft/gpl.html or by writing to</span>
0029 <span class="comment">%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.</span>
0030 <span class="comment">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span>
0031 <span class="keyword">persistent</span> a b c
0032 <span class="keyword">if</span> isempty(a)
0033     a=[1 2 3 4 2 1 4 3 3 4 1 2 4 3 2 1];
0034     b=[1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4];
0035     c=[6 8 10 11 15 16];
0036 <span class="keyword">end</span>
0037 s=size(x);
0038 x=reshape(x,4,[]);
0039 <span class="keyword">if</span> nargin&lt;2 <span class="comment">% one argument - just invert x</span>
0040     m=sum(x.^2,1);
0041     x=x./m(ones(4,1),:);
0042     x(2:4,:)=-x(2:4,:);
0043     q=reshape(x,s);
0044 <span class="keyword">else</span>  <span class="comment">% multiply by conjugate of y and then divide by |y|^2</span>
0045     y=reshape(y,4,[]);
0046     m=sum(y.^2,1);
0047     q=x(a,:).*y(b,:);
0048     q(c,:)=-q(c,:);
0049     q=reshape(sum(reshape(q,4,[]),1),s)./m(ones(4,1),:);;
0050 <span class="keyword">end</span></pre></div>
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